Circle cutter



.Iunez24,' 1930. A. J. LAWRENCE 1,755,799

' CIRCLE CUTTER Filed May "14, 1928 INVENTOR;

TQEWEXI Patented June '24, 1930 ALBERT J. mwmcn, or sr. rant, munso'ra cmcLE cur'rnn Application filed m '14,

My invention relates to a device for cutting circular holes of various sizes as desired in sheet metal, the device'is also useful for a similar purpose for other materials such as sheet fiber wood veneer or other flat materials whic ma be cut by rotary cutting tools as hereina er described. The main object of this invention is to provide a simple highly eflicient circular cutting dem vice applicable for use in drill-presses, lathes or any adapted to be'fed toward a base plate on which is secured a plate element to be worked on. In theaccompanyingdraw- 9 ig. 1 i s .a top view of my device in o er ative posltion about to cut a circular ole,

in a piece of sheet metal laid on a base plate. I 4 Fig. 2 is a front elevation of Fig. 1 with some added details. v Fi isv a side elevation of the spindle of my evice. I f I Figs. 4 and5 are respectively top and side elevations of the primary cutter bar tool A which is detachabl securable ina chuck 1 of the device and Fig. 6 is a front view ofthe cutting portion of the toolA looking towards Fig; 5 from the right, and

a modification of said cutting part;

Figs. 7, 8 and 9 are, respectively, front detail views of; cutting bars B, Cand D showing only the cutting elements thereof, the upper parts of all cutter bars being practically identical and said cutters being used successively in the order in which they are lettered. l A

Fig. 10 is a greatly enlarged sectional detail of a portion of a plate" to, be cut and 40 showing t e preferred manner of making .-cuts therein with the four cutting tools.

Referring to the drawing by reference numerals and letters, 1 des one piece chuck of cylindrica form with a square central bore 2 and-a number of longitudinal rectangular grooves 3 cutinto its exterior circular face said grooves 3 being shown-as 4. innumber and equally ace The bottom of each groove is form with 60 a longitudinal innerand central rotmded other machine having a rotary spindleates a solid.

192s. serialize. 277,538.

groove 4 serving as a keyway for a corresp'ondin 1y ribbed filler block 5 said block fitting a so snugly in the groove 3. Each said block. 5 has an outer groOve3-4 correspondin to the similarly numbered parts of the c uck of said grooves being normally vertical. Each cutter bar is formed at one sidewith a rounded rib :G'adapted to be fitted in either the groove 4'. of the filler blocks or the corres onding roove 4 in the chuck where the ut am? rear vertical sides of each bar fits snugly within groove 3. The lower and cutting element of the bars are of various sha es for a purpose presently to be describe said lower ends being reduced downwardly-as best shown in Fig. .6 and their. cutting elements being arrangedin a predetermined order. The cutter bars are rovided in; corresponding (pairs arranged d etachabl as described in iametrically op osite si es of the chuck-and 7 are longitu nal apertures in the shank of said cutter bars arranged for passing a threaded bar 8 therethroug Each said threaded bar extends diametrically through the chuck and extends with its opposite threaded ends .outwardly of its pair of cutter bars and 9 are threaded nuts one for each end of said threaded bar and adapted to be turned to engage and rigidly hold the adjacent cutter bar as best shown in Figs. 1 and 2. \p

Where there are four cutter bars employed, as shown, it is obvious that two adjustment rods 8 are required and these are arranged to cross each other within the chuck one 35 above the other therefore making it necessary to have the location of the aperture 7 in the cutter bars correspondingly located. For example the apertures 7 in the cutter bars A and G are at -one elevation while the corresponding apertures in cutter bars B and D are at a-lower elevation. The chuck of this device requires a spindle, the main body portion' of which is square in cross section'to fitsnugly the bore a 2 of the chuck, said body portion beingdesignated 10B in Fig. 3 and is of course drilled as 10D comprisin two transversely arranged holes through w ich the bolts 8 are passed. The'exterior portion of this spindle comprises a suitable shank S of any redetermined length and diameter and whic is insertable in suitable rotary s indle engaging means and base 12 below which it is is securely held.

means such as a clamp 16 may be used to 1 hold the edge portion of said plate 14 tight are oi various sha are used in certain prearranged order. A-

I ting Fi s. 1 and 10, into the plate material 14' and on a predetermined diameter. The dicutting against the plank and preventing rotat on o the plate when the cutting operation be 'ns.

previously mentioned the cutter bars es and their cutting ends might be considered the primary cutter, its element comprising preferably a grooved cutting end 17 which simply cuts into the metal lightly and practically cutonly two concentric circles as 18 in ameter is of course determined by the thickness of the filler blocks or gage blocks 5 which maybe provided in setsof various ably Fig.7 at 20." Said rounded cutting edge 20 *thiclmess'esowith each chuck. Thus for example an eight inch circle may be cut by putting in filler blocks 5 of the pro er thickness to space the cutter bars wit the cutting elements exactly four inches from the center of the chuck.

The secondary cutter of my device follows cutter A and is of course spaced ninety as is readily understood from 1m which the arrow 19 designates the direction of rotation. Said cutter B is prefernarrow and round. as best shown'in ,cuts a slight groove 20G between the cuts 18 rev-iously made rounded cutting edge 21- cutting a lijdeeper -a square cutting edge 22 (see Fig. 9) which 1 removes the balance of the material 'between the grooves 18 as to the dotted'line 22G in Fig. 10. In Fig. 6 the small detail to the right indicates the grooved cutter part shape, or sharpened.

It is obvious that the cutting ends of the tools A, B, C, and D may be of various. de-

lank 18 .vice

by cutter A. The cutter 'ar designated C as a more shallow but mg a central poly onal of A in two parts designated A and A of i 'which'A is detachably. sequred to A, as with. screws A, this construction providingfor one half ofthegroove 17 in each part and which is thus more easily ground to right I refer to-use a primary cutter with a lower art of Fi 5 while the dotted V- shape no in sai figure indicates a preferred shape of the cutting ends of the tools following the primary cutter.

It will be readilylunderstood that for cutting out circular pieces of small diameter it may be necessary to make a curvature rearwardly of each cutting element said curvature being of course inwardly directed so as to provide clearance when thedevice is in operation. However the main object of this cutting apparatus-is to make compara-' tivel large circular cutouts in sheet metal point as shown in full'lines in the and eaving clean cut edges in the aperture.

the cutters it being readily understood that the o ration continues b feedin the deownwardl gradua y into t e metal until it is cut t ough. It is obviousthat when the tools make the final cut the cen-, tral circular disc is held rigid by the be t 15 and the main part of the plate is suitabl held rigid and there is no possibility of said out out circular part becoming loose and damaging the cutting members.

The above specification fully discloses the construction and operation of my device. It will be readily understood that any modifications of the structure such as providing a larger number ofcutters, or variation in the shape of the cutting elements will come within the spirit and scope of the invention. A wood block 13 has been specified as a base for the sheet metal 14 to be clamped upon as 1t has been found best for the purpose described and when the cutting tools go throu%h the metal their cutting edges are not e mziy be used.

n the art it has hitherto been common practice to make circular holes in sheet metal or other plate material by first drillmg a circular row of small-holes, then chipping out the metal between them'and filing or grinding the aperture to proper contour, a tedious and unsatisfactory method, in comparison with which the accuracy and speed of my device is readily seen.

I'claim;

the combination of'a cylindrical chuckhavmg a number of equally spaced lo oo'ves in its exterior face, said chuck havbe r with one end s :to lit removably in said bore and a roun concentric sh por tion' normally exteriorly of the chuck body,

ected. Any other equivalent base ngitudinal In a circle cutterof the class described,

bore a shank memt latter means comprising for each pair of diametrically opposite cutter bars a. bar

' threaded at both ends and passed diametrically through the chuck and said bars and. a 5 nut exteriorly of each cutter bar, threaded on said bar to clam said pairs of cutter bars inwardly end to frlctionally retain each bar in its groove, and gage blocks for said grooves provided in sets; each block having a longitudinal ribvarranged to fit in one of said grooves of the chuck and an outer groove adapted to snugly receive a cutter bar and said blocks provided with elongated apertures corresponding to the aperturesof the cutter bars.

In testimony whereof I afiix my si nature. Q M

ALBERT J. LAWRE CE. 

